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Pan, Tilt and Zoom Dome Camera / ACD-1500-HT35
Multiple PTZ (cont.)
Some circumstances require the use of a star configuration. The termination resistors must be set on the
two devices that are the farthest distances away from each other, in this case #1 and #15 as seen below.
As the star configuration does not conform to the RS485 standards, problems such as signal reflection
and lower anti-interference performance arise when the cable runs are long. In addition, the reliability of
control signals are decreased which may cause the PTZ to respond intermittently, not respond at all, or
operate a single command continuously without ever stopping. In these circumstances, the factory
recommends the use of an RS485 distributor (DR-HB16). The distributor can change the star
configuration connection to the mode of connection stipulated in the RS485 standards. With the
distributor, reliable data transmission can be received.
PTZ and RS-485 Basics
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